Perform a retrospective cohort study of the risk of gallbladder and other hepatobiliary diseases related to the use of oral contraceptives. Using data from the Walnut Creek Contraceptive Drug Study, supplemented with data to be obtained from review of the Kaiser Permanente Medical Care Program records, a comparison will be made of women who have been exposed to steroid contraceptives on the occurrence of hepatobiliary disease in women. The contribution of length and cumulative level of estrogen/progestin exposure to the risk of these diseases will be quantified.